(refers to 7" ring gear rears only)


So a common swap is the Kia 4.78 ring and pinion or the entire 3rd member. But I'm looking into other factory gear options. The NA FC also has a 7" ring gear. So could you use NA FC rear end chunks in GSL-SE rear end?


I know you can bolt the 94-97 Maita 3rd member into a 84-85 Rx7 housing without any other mods also. But what are the gear options?

 

I don't know if this link has all the information that you are looking for but should be a good start. To find more info just search with the term "Miata" and use the advanced search option to see the threads with the most responses.

https://www.rx7club.com/showthread.p...ighlight=miata

 

That is a great link. But what I really want to know is if you can swap ring and pinions between 1st gen GSL-SE rears and NA FC diffs? Or my actual goal is the Kia 4.78 ring and pinion into the NA FC diff...

I want to use the 4.78 from the Kia like the 1st gen guys do. But i want to use it in my NA FC diff. I know that they are both 7" ring gears. I have been told in the past that if you break your GSL-SE rear, the 3rd member from the NA FC diff will work just fine. Leading me to believe that the Kia ring and pinion could also work in the FC diff...???

 

I'm too lazy to look myself, but check out Mazdatrix or RB websites and see if they have different part #'s for 84-85 SE's and the FC rings. Many times the parts (like clutches) are listed 84-91.

 

After looking at the Mazdatrix and Racing Beat site, I'm guessing that this is not possible. The 72-85 pinions are very short, and the 86-92 uses a very long pinion gear.

 

I went with racingbeats 4.875 installed in my GSLSE rear diff. Absolutely love them! Actually hooks better and launches great. I lose 1000 rpm on the highway but a S4 or S5 n/a tranny will compensate for about 500 rpm. I have one but I am waiting for mine to break to make the swap worthwhile as i don't mind the highway rpm since I do mostly all city driving.

 

Rings and pinnions must stay together once used. You cannot use the FC ring or pinnion. The only thing that works is the FC LSD. If you're looking I have 4.1 and 4.44s for sale.